1. Field of Invention
This invention pertains to an improved cage assembly for confining laboratory animals having a watering manifold mounted on the cage to allow the animals to be supplied with water from an outside automatic watering system.
2. Description of the Related Arts
In the care and feeding of laboratory animals, several systems have evolved over the past 50 years or so. The earliest of these systems is known as a "horsestall" system which includes a number of wire stalls in which the laboratory animals are housed and a trough running outside of the stalls which contains water and other nutrients. The laboratory animals can stick their heads through the wire cage and drink from the trough. Such a system for feeding poultry is shown in U.S. Pat. No. 3,916,837 issued to Murato on Nov. 4, 1975. The disadvantage of the "horsestall" cages, such as Murato is the danger of crosscontamination between animals in adjacent stalls and through the water in the common trough. Also, the cages cannot be easily removed from the system and brought to a work station where the animals can be handled or treated.
Some of the problems with the "horsestall" system were solved by a system of cages which comprised a number of stainless steel "shoeboxes" placed on a rack. Each stainless steel "shoebox" has an open wire mesh bottom for the disposal of droppings and fluids. The "shoeboxes" are supplied with drinking water from a centralized outside watering system. A "shoebox" system is illustrated in the U.S. Pat. No. 3,585,968 issued to Stone, Jr. on June 22, 1971. Although preferable to the old "horsestall" system, this system suffers from several other drawbacks: First, the steel cages are not easily removable from the rack for observation and treatment of the animals. Second, the stainless steel "shoeboxes" are not transparent so that the animals do not get an adequate supply of sunlight and the animals cannot be easily observed. Third, the individual "shoeboxes" are not biologically isolated from one another, having a substantially open bottom, perforated sides and an open entrance for each individual watering tubes. If, however, the bottoms were closed, and the individual watering tubes were sealed off, then these cages would suffer from the additional problem of flooding because excess water constantly drips from the watering tubes and would flood the cages.
Some of the problems of the "shoebox" type cages have been solved by complicated systems such as the one disclosed in U.S. Pat. No. 3,924,571 issued to Holman on Dec. 9, 1975 which discloses a number of totally enclosed cages with the very complicated germ free ventilation and watering system. The problem with rack system is that it is expensive and although it offers a rack with individual environments for the laboratory animals which do not cross-contaminate, the individual cages cannot easily be removed from the rack for treating, handling or observing the animals.
Another complicated and expensive cage assembly is disclosed in U.S. Pat. No. 3,877,420 issued to Eagleson, Jr. on Apr. 15, 1975. However, this cage suffers from the same drawbacks as the U.S. Pat. No. 3,924,571 Holman patent in that it is complicated, expensive and not easily portable.
The watering systems for supplying water to the "shoebox" and "horsestall" cage systems has been improved over the years. One such improved watering system is disclosed in U.S. Pat. No. 4,055,147 issued to Fletcher, et al. on Oct. 25, 1977 which discloses an automatic fluid dispenser that will only dispense water to cages at predetermined times. Also, water on demand watering tubes have recently been developed which dispense water when the animal licks a small ball or pin at the end of the watering tube. Three such water on demand watering tubes are disclosed in U.S. Pat. Nos. 3,228,377 issued to Grassano on Jan. 11, 1966, U.S. Pat. No. 4,346,742 issued to Niki on Aug. 31, 1982 and U.S. Pat. No. 4,458,632 issued to Niki on July 10, 1984. The U.S. Pat. Nos. 4,346,472 and the 4,458,632 issued to Niki also provide for a small guard on the bottom of the watering tube to allow excess water to drain out of the cage so that the cage does not flood. However, use of these water on demand watering tubes does not solve the problems of the "horsestall" or "shoebox" systems of cross-contamination, portability and non-transparency.
The most inexpensive and popular cages now in use are polycarbonate cages. Polycarbonate cages are relatively inexpensive, transparent and are readily portable. Examples of early polycarbonate cages and accessories thereof are disclosed in U.S. Pat. Nos. 3,358,649; 3,518,971; 3,752,124 and 4,334,500. The major disadvantage of these cages was the problem of cross-contamination between adjacent cages or contamination by the surrounding environment.
By adding a filtered top to the early polycarbonate cages, the problem of cross-contamination has been solved and a biologically micro-isolated environment is formed within each cage. Several micro-isolated polycarbonate cage assemblies have been developed, for example, U.S. Pat. Nos. 4,480,587; 3,613,639; 3,528,390; 3,528,227; 3,343,520; 5,537,428; 3,304,913 as well as G.B. Pat. No. 2,065,440 and European Pat. No. 0,036,628. Typical of the biologically micro-isolated polycarbonate cage assemblies is the "Animal Cage Assembly with Reuseable Filter Cap" disclosed in U.S. Pat. No. 4,480,587 issued to Sedlacek on Nov. 6, 1984. The Sedelak patent discloses a polycarbonate cage, a wire cage lid which was first disclosed in U.S. Pat. No. 3,358,649 issued to Gabriel, et al. on Dec. 19, 1967, and a filter cap for micro-isolating the cage from the outside environment. The laboratory animals are supplied with water from a water bottle placed in a compartment on the wire cage lid with a watering tube extending into the confined space below. Although these micro-isolated polycarbonate cage assemblies are substantially biologically micro-isolated from the outside environment, transparent and easily transported to various locations, a number of problems still remain with regard to these cage assemblies. First, the water bottles have to be changed periodically and autoclaved. Changing the water bottles and autoclaving requires approximately 12 steps, many of which must be done by hand under sterile conditions inside a HEPA (High Efficiency Particulate Air) filtered hood, and require the use of an autoclave costing approximately $100,000.00 or more. In addition, use of a watering bottle which must be changed causes other problems, such as, upsetting the biorythems of many of the nocturnal laboratory animals, retinal and other diseases caused by pseudonymous bacteria building up in the lip of the watering tube prior to changing or due to insufficient autoclaving.
None of the related art teaches or discloses a manner of connecting the biologically micro-isolated polycarbonate cage assemblies, such as the one disclosed by Sedalek, to an outside watering system without destroying the integrity of the micro-isolated environment of the cage. Merely inserting a water on demand tube, like the one disclosed by Niki, through the wall of a micro-isolated cage assembly, such as the one disclosed by Sedelak, would result in a host of new problems. First, excess water would stay at the bottom of the cage assembly creating a new contamination problem. Second, the cage could not be easily removed from the outside watering system for treatment, observation or handling of the confined animals without destroying the integrity of the biologically micro-isolated cage from the environment. Third, the water dispensers disclosed by Niki include a small aperture which would destroy the integrity of the biologically micro-isolated of the cage assembly from the outside environment.
U.S. Pat. No. 4,365,590 issued on Dec. 28, 1982 to Ruggieri, et al., exemplifies one attempt which has been made to combine a water on demand tube from an outside watering system with a polycarbonate cage. The Ruggieri, et al. system discloses a ventilated rack connected to an outside ventilation and an outside watering system and a plurality of open cages which are placed in the rack. Each cage has an opening in its wall and an access port mounted in the opening and attached to the wall with a press fitted ring on the outside of the aperture. The confined animal can drink by sticking its tongue through the access port and licking the water on demand tube outside the cage. Excess water collects in a trough under the watering tube. Several problems, however, still remain with the system of Ruggieri, et al. First, the problem of cross-contamination is not entirely solved. The cages are open, and the access port remains permanently open to allow cross-contamination from air within the rack. Second, if power were lost to the ventilation system of the rack the cages would cross-contaminate through their open tops their and open access ports. Third, the ventilated rack is complicated, very expensive and must be periodically cleaned and sterilized or it would present a much greater contamination problem then the individual cage assemblies.
Accordingly, it is an object of the present invention to solve the problems inherent in the related art by providing an improved cage assembly which is biologically micro-isolated from the outside environment and eliminates the need for a watering bottle.
It is another object of the present invention to provide an improved cage assembly which is biologically micro-isolated from the outside environment and supplies water on demand to the caged animals.
It is still a further object of the present invention to provide a cage assembly which is biologically micro-isolated from the outside environment and may be easily moved for treating, observing or handling caged animals by removing an cage assembly from an outside watering system without destroying the integrity of the biologically isolated cage from the outside environment.